Monday, September 24, 2007


Vegetable is a culinary term which usually refers to an edible part of a plant. The definition is traditional rather than scientific and is somewhat capricious and subjective. All parts of herbaceous plants eaten as food by humans, entire or in part, are normally considered vegetables. Mushrooms, though belonging to the biological realm fungi, are also commonly considered vegetables. In general, vegetables are thought of as being savory, and not sweet, even though there are many exceptions. Nuts, grains, herbs, spices and culinary fruits (see below) are usually not considered vegetables.

Thursday, September 13, 2007


100 A clock is an instrument for measuring time. A clock is typically a physical instrument; an especially accurate one is called a chronometer. The clock in its current form has been in use since at least the 14th century. Clock can refer to a conceptual system of time measurement.


A windup alarm clock Clocks are in homes and offices; smaller ones are carried; big ones are in civic places, e.g. a train station or church. A small clock is often shown in a corner of computer displays or mobile phones.

The major purpose of a clock is not always to display the time. It may also be used to control a device according to time, e.g. an alarm clock, a VCR, or a time bomb.

Practically all computers depend on an exact internal clock signal to allow synchronized processing. Some computers also maintain time and date for all manner of operations whether these are for alarms, event beginning or just to display the time of day.

Ideal uses
An ideal clock procedures the ratio of the duration of natural processes, and thus will give the time measure for use in physical theories. Therefore, to define an ideal clock in terms of any physical theory would be circular. An ideal clock is more suitably defined in relationship to the set of all physical processes.

A clock is a repeated, periodic process and a counter.
A good clock is one which, when used to measure other repeated processes, finds many of them to be periodic.
An ideal clock is a clock that makes the most other repeated processes periodic.
The recurrent, periodic process is an oscillator and typically generates a clock signal. Sometimes that signal alone is called "the clock", but sometimes "the clock" includes the counter, its indicator, and everything else supporting it.

This definition can be further improved by the consideration of succeeding levels of lesser and lesser error tolerances.

Thursday, September 06, 2007


Tumor or tumour is an irregular growth or mass of tissue. A tumor can be either malignant or benign. Almost all tumors are examples of neoplasia, although certain developmental malformations or inflammatory masses may occasionally be referred to as tumors.

Neoplastic tumors are caused by mutations in DNA of cells, which interfere with a cell's capability to regulate and limit cell division. An accumulation of mutations is needed for a tumor to emerge. Mutations that activate oncogenes or repress tumor suppressor genes can eventually lead to tumors. Cells have mechanisms that repair DNA and other mechanisms that cause the cell to destroy itself by apoptosis if DNA damage gets too severe. Mutations that repress the genes for these mechanisms can also ultimately guide to cancer. A mutation in one oncogene or one tumor repressor gene is usually not enough for a tumor to occur. A combination of a number of mutations is essential.